The present invention relates to supporting and guiding a punch or mandrel for punching presses, cold extrusion molding, or the like; in particular, for backward extrusion of hollows.
Guiding a mandrel or punch during piercing of a blank or of the die punch or mandrel during backward cold extrusion is a rather critical requirement in order to avoid eccentric deformation of the work. Usually, the mandrel or punch is guided by a load-bearing support in the upper tool portion so that underneath the work can still be displaced laterally, particularly in the first phase of piercing. This, however, is the most critical situation as a very accurate centering of this initial piercing and identifying step is a prerequisite for obtaining uniform wall thickness over the entire length of the work.